Fuel cell systems, when left in a continuously halted state for a long time under low-temperature circumstances such as outdoors in cold climate areas, may suffer from freezing of water content within the systems. Accordingly, various methods have been conventionally proposed for preventing freezing of fuel cell systems.
JP 2005-267961 A discloses a technology concerning a fuel cell system for performing a so-called intermittent operation by switching between a power generation state and a halt state in accordance with electric power required by an electronic vehicle, a charged state of a secondary battery, and so on. In this system, when there is a possibility that the fuel cell will freeze, the intermittent operation is prohibited, thereby increasing the output power of the fuel cell to prevent freezing.
JP 2004-153947 A discloses a technology concerning a hybrid car equipped with a fuel cell system and an engine. According to this technology, when an outside temperature is lower than a predetermined reference temperature, power generation by the fuel cell is prohibited and desired electric power is obtained by the engine.
JP 2005-251576 A discloses a technology, in a fuel cell system, for performing a scavenging processing to remove water content within the fuel cell when there is a possibility that the fuel cell will freeze while the system is halted.
In this regard, when a vehicle in which a fuel cell system is mounted travels by using electric power generated by the fuel cell system in the low temperature circumstances, there is a possibility that the relative wind generated in association with running of the vehicle may cause freezing of a component forming the fuel cell system.